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(No Model.)

PER OSCAR SUNDIN.

I SURFACE PLATE.

No. 326,925. Patented sept. 2z, 1885.

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UNITE STATES A'rsNT Finca.

PER OSCAR SUNDIN, OF PROVIDENCE, RHODE ISLAND.

SU RFACE-PLATE.

SPECIFICATION forming part of Letters Patent No. 326,925, dated September 22, 1885.

Application filed New mbcr 7. 18r4.

To all whom/ it may concern:

Be it known that I, PER OsoAR SUNDIN, a subject of the King of Sweden, residing at Providence, in the State of Rhode Island, have invented an Improvement in Surface Plates,of which the followingis a specification.

My invention relates to an improvement in surface-plates or tools for testing surfaces and straight-edges for mechanical use, in which a top and bottom plate are connected by means of side and end plates conjointly with interior ribs; and my invention consists in the irnproved diagonal arrangement of the interior ribs, as hereinafter set fort-h.

Figure lis a top view of my improved surface-plate. Fig. 2 isa side elevation of the same. Fig. Sis a horizontal section taken in the dotted lineX X of Fig. 2. Fig. 4 is an end elevation. Fig. 5 is a tranverse section taken in the dotted line Y Y of Figs. l and 3. Fig. 6 represents the bottom view of the plate. Fig. 7 is a longitudinal vertical section taken in the dotted line Z Z of Figs. l and 3.

In the accompanying drawings, K is the top plate, and L the bottom plate, made of equal thickness of cast-iron, and connected to each other by means of the side plates,I Land end plates,O O, and the thinner interiorribs,D,E, and F, cast integrally with the plates K and L. The ribs E E,made thinner than the plates K and L, extend from one side to the other parallel with and near the end plates,O O,and the ribsF F F F, which connect the ribs E with the adjacent end plates, O,serve to impart the required strength and rigidity to the ends of the surfaceplate.

In surfaceplates of large size I cast an extra rib, G, extending centrally from side to side, and parallel to the ribs E E, as shown by the dotted line G in Figs. 3 and 7.

The central interior portion of the plate is occupied by the longitudinal central rib, F, and by the diagonal ribs D and D', all made thinner than the plates K and L, and cylindrical enlargements A A A are formed at the intersection of the rib F/ and ribs D with the cross-ribs E E, such enlargements being made to extend from the top to the bottom plate in line with the axis of the studs or legsAA A, which project from the bottom plate,L,and are preferably made integral with the same5but in some instances they maybe screwed in.

(No model.)

rIhe enlargements A A A are arranged at equal distances on both the ribs E E, so that they will always coincide with the IegsA,even if the pattern of the lowerplate is reversed in the molding.

A longitudinally directed cylindrical enlargement, B, is made in the center of the central rib,F', in line with the rib F, and from the center of the end plates, O O, holes O C are drilled into the axis of the enlargement B,the holes O O being adapted for the reception ot' free handles or centers, whereby the plate can be lifted either by hand or by means of hoisting machinery, and can be left hanging at any required angle.

M M are the holes formed in the bottom plate, L, by the core-prints, necessary for setting the cores for the interior chambers, and for the eX'- traction of the cores from the chambers, and the core-holes M in the bottom plate willserve for the free access of air to the interior chambers, thus securing an even temperature throughout the plate,whereby the rate of con-' traction and expansion of the top and bottom plates will be equalized.

The side plates, I I, end plates, O O, and the top and bottom plates,K and L,are to be planed over, after which the top', sides, and ends can be scraped to practicallyv plane surfaces and made square with each other, the top surface, K, being in ordinary cases the main surface to be used.

An annular depression, N, is formed in the bottom plate around each ofthe three legs A,in order to avoid contact of the planing-tool with the legs A in planing off the surface of the bottom plate.

My improved surface-plate is thus constructed so that several surfaces can be scraped on the same plate-namely, the top, sides, and ends-thereby enabling the workman to test the condition of one of thesurfaces by the application thereto of astraight-edge scraped to coincide with the plane ofthe least-worn surfaces.

In my improved surface-plate, the ribs being made slightly thinner than the planed top and bottom plates and side and end plates, a uniform degree of contraction and expansion will be secured throughout the plate, as it is well known to mechanics that two pieces of cast-iron of the same dimensicns,one left rough IOO from the mold and the other planed and iinished, do not receive heat from the surrounding atmosphere or impart the same with equal facility.

By the employment of aproperly-constructed cast-iron plate having a practically-plane surface it is practicable to make the special scraped parts of a machine long before the main body of the machine is constructed or made, and to be able to enga-ge several men on the same work, where only one man could be employed if one part should be scraped tothe other.

The piece of work which is to be scraped to a perfectly flat surface by means of the surface-plate should be first scraped over once before it is applied to the. surface of the same, otherwise it is liable to" injure the plate. The surface-plate being first slightly rubbed over with red-lead the scraped piece of work is to be applied to the surface of the same,or in cases where the piece of work istoo heavy to apply to the plate, the plate can be applied to the'work, to show where the two surfaces touch each other, and the points on the surfaces of the work, which are by this means shown to be higher than others, are to be scraped off continuously until the piece exactly fits the surface-plate.

By the employment of three legs, A A A, extending downward from the under plate,the air will have free passage under the same when at rest upon a suitable support, and will also have free access to the interior chambers through the holes M in the bottom plate. The legs will at the same time prevent accidental contact with an uneven and rough resting surface, which might cause injury to the exactness of the scraped surfaces of the plate.

The diagonal ribs D are located in a direct line from the opposite corners of the plate,and thus cross each other at the center of the same, and the ribs D' start from the longitudinal central rib, F, and run parallel with the diagonal ribs D, until they intersect with the side plates, I I, and by reason of the peculiar arrangement of the ribs D and D thesurfaceplate is made to stand the severest tests with regard to its rigidity and'accuracy, being far superior in'this respect to the ordinary surface-plate.

I claim as my invention- 1. A surface-plate having top and bottomV plates, K L, side plates, I l, end plates, O O, longitudinal rib F,parallel to the side plates, diagonal ribs D D,in a line extending from corner to corner of the plate, and the ribs D' D', extending from the rib F' parallel with the ribs D D, substantially as described.

2. A surface-plate. having top and bottom plates, K L, side plates, I I, end plates,O O, ribs E E, parallel to the end plates,0 O, ribs F F, which connectthe ribs E E with the end plates. rib F', parallel to the side plates, diagonal ribs D D,in a line extending from corner to corner ot' the plate,and the ribs D' D', extending from the rib F' parallel With the ribs D D, substantially as described.

PER OSCAR SUNDIN. Witnesses:

MARsToN LINCOLN, OSCAR LAPHAM. 

